Structure Design Of Parallel Mini-channel Cold Plate For Thermal Management Of Lithium-ion Battery

With the rapid development of the global economy,the concept of environmental protection has gradually taken root in the hearts of the people,and the development of the new energy electric vehicle industry has received more and more attention.The core component of an electric vehicle is the battery pack,and a thermal management system needs to be introduced to ensure that the battery pack works within a suitable temperature range.Among various cooling technologies,liquid cooling is one of the most important ways for battery thermal management.Parallel mini-channel cold plate has the advantages of high heat exchange efficiency,low energy consumption,compact structure,and good packaging,so it is widely used in battery thermal management system.However,the parallel mini-channel structure is easy to induce uneven flow distribution,which affects the cooling performance of the cold plate.Existing research mainly adopts experience or parameter trial matching methods to design cold plates.It lacks of universal and effective optimization method for designing cold plates.This thesis investigates the influence of the parameter on the system performance,proposes structure design method and develops fast calculation model for parallel mini-channel cold plates in battery thermal management system.The following conclusions can be obtained:(1)Numerical simulation method is used to study the performance of parallel mini-channel cold plates with different flow patterns(Z-type,U-type,and I-type),and its accuracy is verified by experiments.By adjusting the edge width,changing the convergence channel width,and constructing the symmetrical structure,the performance of the cold plate is significantly improved.Under different flow rates,compared with the original I-type cold plate,the designed cold plate reduces the temperature difference and energy consumption of the cold plate by more than 44% and 71%,respectively.Moreover,non-dimensional analysis results show that the inlet temperature and heating power do not affect the optimal structure of the parallel mini-channel cold plate.(2)The cold plate is used to cool the battery pack,and the influence of the relative direction of cold plate channel and the battery arrangement on the battery temperature is analyzed.The numerical results show that when the parallel channel direction and the battery arrangement direction are perpendicular,the battery temperature and temperature difference are small.Compared with that of original system,the temperature difference of battery pack and the energy consumption of designed symmetrical I-type cold plate are reduced by 83% and 74%,respectively.(3)For cooling large-scale battery packs,a bidirectional symmetrical parallel mini-channel cold plate is constructed and its outlet positions are adjusted to improve the cooling performance and reduce the energy consumption of the cold plate.Compared with the battery thermal management system with the original cold plate,the one with the designed cold plate respectively reduces the battery temperature difference and energy consumption of the cold plate by 77% and 82% under different mass flow rates.(4)A flow resistance network model is introduced to calculate the channel velocities in the parallel mini-channel cold plate.The results of the model agree well with the numerical results.The maximum deviation of the model results is 9.4%.The flow resistance network model can be applied to evaluate the performance and design the structure of parallel mini-channel cold plates.